Abstract
Microalgal storage lipids are considered to be a promising source for next-generation biofuel feedstock. However, microalgal biodiesel is not yet economically feasible due to the high cost of production. One of the reasons for this is that the use of a low-cost open pond system is currently limited because of the unavoidable contamination with undesirable organisms. Extremophiles have an advantage in culturing in an open pond system because they grow in extreme environments toxic to other organisms. In this study, we isolated the acidophilic green alga Pseudochlorella sp. YKT1 from sulfuric acid mine drainage in Nagano Prefecture, Japan. The vegetative cells of YKT1 display the morphological characteristics of Trebouxiophyceae and molecular phylogenetic analyses indicated it to be most closely related to Pseudochlorella pringsheimii. The optimal pH and temperature for the growth of YKT1 are pH 3.0–5.0 and a temperature 20–25°C, respectively. Further, YKT1 is able to grow at pH 2.0 and at 32°C, which corresponds to the usual water temperature in the outdoors in summer in many countries. YKT1 accumulates a large amount of storage lipids (∼30% of dry weigh) under a nitrogen-depleted condition at low-pH (pH 3.0). These results show that acidophilic green algae will be useful for industrial applications by acidic open culture systems.
Highlights
Microalgae have come to be seen as a promising source of next-generation biofuel feedstock that can be produced without compromising the production of food, fodder and other products derived from crops [1,2]
Sustained and reliable cultivation of a single species in open pond systems can be encouraged by cultivating extremophiles that tolerate a particular environment that is lethal for other species [3]
Isolation and Morphology of the Acidophilic Algal Isolate In order to isolate acidophilic algae, acidic mine drainage (AMD) from an abandoned sulfur mine were sampled in Nagano Prerefecture, Japan on 6th September 2013
Summary
Microalgae have come to be seen as a promising source of next-generation biofuel feedstock that can be produced without compromising the production of food, fodder and other products derived from crops [1,2]. To determine the optimal temperature condition, cells were diluted to an OD750 of 0.5, in M-Allen medium pH 3.0 and cultured at several temperatures (from 10 to 35uC) under continuous light (90 mE/m2?s) with aeration (0.25 l ambient air /min) for 24 h.
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